def circular_shifts(iterable, steps=1):
    """Return a list of circular rotations of *iterable*.

    >>> circular_shifts(range(4))
    [(0, 1, 2, 3), (1, 2, 3, 0), (2, 3, 0, 1), (3, 0, 1, 2)]

    Set *steps* to the number of places to rotate to the left
    (or to the right if negative).  Defaults to 1.

    """
    buffer = deque(iterable)
    if steps == 0:
        raise ValueError('Steps should be a non-zero integer')

    buffer.rotate(steps)
    steps = -steps
    n = len(buffer)
    n //= math.gcd(n, steps)

    return [buffer.rotate(steps) or tuple(buffer) for _ in repeat(None, n)]